English verb conjugation
COULD RETAIN

Regular verb: retain - retained - retained

Affirmation

Simple form	V-ing form
I could retain you could retain she could retain we could retain you could retain they could retain	I could be retaining you could be retaining she could be retaining we could be retaining you could be retaining they could be retaining
Perfect	V-ing perfect
I could have retained you could have retained she could have retained we could have retained you could have retained they could have retained	I could have been retaining you could have been retaining she could have been retaining we could have been retaining you could have been retaining they could have been retaining

Negation

Simple form	V-ing form
I could not retain you could not retain she could not retain we could not retain you could not retain they could not retain	I could not be retaining you could not be retaining she could not be retaining we could not be retaining you could not be retaining they could not be retaining
Perfect	V-ing perfect
I could not have retained you could not have retained she could not have retained we could not have retained you could not have retained they could not have retained	I could not have been retaining you could not have been retaining she could not have been retaining we could not have been retaining you could not have been retaining they could not have been retaining

Interrogative form

Simple form	V-ing form
could I retain? could you retain? could she retain? could we retain? could you retain? could they retain?	could I be retaining? could you be retaining? could she be retaining? could we be retaining? could you be retaining? could they be retaining?
Perfect	V-ing perfect
could I have retained? could you have retained? could she have retained? could we have retained? could you have retained? could they have retained?	could I have been retaining? could you have been retaining? could she have been retaining? could we have been retaining? could you have been retaining? could they have been retaining?

Interro-negative form

Simple form	V-ing form
could I not retain? could you not retain? could she not retain? could we not retain? could you not retain? could they not retain?	could I not be retaining? could you not be retaining? could she not be retaining? could we not be retaining? could you not be retaining? could they not be retaining?
Perfect	V-ing perfect
could I not have retained? could you not have retained? could she not have retained? could we not have retained? could you not have retained? could they not have retained?	could I not have been retaining? could you not have been retaining? could she not have been retaining? could we not have been retaining? could you not have been retaining? could they not have been retaining?